Method and apparatus to sense the environment using coupled microphones and loudspeakers and nominal playback

Abstract

An electronic device having a device housing includes a loudspeaker and several microphones within the device housing. A control circuit is electrically coupled to the loudspeaker and microphones. The loudspeaker produces speech and/or music. The control circuit determines a statistical measure for a first data set representing individual impulse responses from the plurality of microphones and compares that to a predetermined statistical measure for a second data set representing individual object-free impulse responses from the plurality of microphones to determine if an object is near the device. The statistical measure may be variance and may be computed in the time domain. Variance may be calculated using differences between the individual impulse responses and a mean impulse response that is a linear combination of the impulse responses for the plurality of microphones. The control circuit may include echo cancellers to mitigate common signals and/or other acoustic sources.

What is claimed is: 
     
       1. An electronic device comprising:
 a device housing; 
 a loudspeaker contained within the device housing; 
 a plurality of microphones contained within the device housing; 
 a control circuit electrically coupled to the loudspeaker and the plurality of microphones, the control circuit providing an output signal to the loudspeaker, the control circuit receiving input signals from the plurality of microphones, wherein the input signals are generated by the plurality of microphones sensing sounds output by the loudspeaker based on the output signal, wherein the control circuit is configured to perform analysis operations including:
 determining, based on the input signals, individual impulse responses from the plurality of microphones, 
 determining a first statistical measure of the individual impulse responses, 
 retrieving a second statistical measure, wherein the second statistical measure is of individual object-free impulse responses from the plurality of microphones, and 
 comparing the first statistical measure with the second statistical measure to determine if an object is near the device. 
 
 
     
     
       2. The electronic device of  claim 1  wherein the first statistical measure is a first variance and the second statistical measure is a second variance, wherein the first variance is calculated using differences between the individual impulse responses and a mean impulse response that is a linear combination of the individual impulse responses for the plurality of microphones. 
     
     
       3. The electronic device of  claim 2  wherein the linear combination of the individual impulse responses for the plurality of microphones are weighted with linear weights chosen such that the variance is minimized. 
     
     
       4. The electronic device of  claim 1  wherein it is determined that an object is near the device if the difference between the first statistical measure and the second statistical measure is larger than a predetermined threshold. 
     
     
       5. The electronic device of  claim 1  wherein the control circuit includes one or more echo cancellers configured to mitigate effects of at least one of common signals and other acoustic sources in the vicinity of the electronic device. 
     
     
       6. The electronic device of  claim 1  wherein the electronic device further comprises a plurality of loudspeakers and the control circuit provides output signals to the plurality of loudspeakers such that the plurality of loudspeakers radiate more acoustic signal in a first direction than in a second direction. 
     
     
       7. The electronic device of  claim 6  wherein the electronic device further comprises a plurality of equalization filters that are coupled to the plurality of loudspeakers, at least one of the plurality of equalization filters being different from the remaining plurality of equalization filters. 
     
     
       8. The electronic device of  claim 1  wherein the control circuit includes a plurality of echo cancellers configured to estimate the individual impulse responses from the plurality of microphones. 
     
     
       9. The electronic device of  claim 1  wherein the control circuit is configured to perform the analysis operations based at least in part on a selected time-domain region. 
     
     
       10. The electronic device of  claim 1  wherein the output signal to the loudspeaker includes at least one of speech or music. 
     
     
       11. A control circuit for an electronic device that includes a loudspeaker and a plurality of microphones within a device housing, the control circuit providing an output signal to the loudspeaker, receiving input signals from the plurality of microphones, wherein the input signals are generated by the plurality of microphones sensing sounds output by the loudspeaker based on the output signal, and wherein the control circuit is configured to perform analysis operations comprising:
 determining, based on the input signals, a first statistical measure of individual impulse responses from the plurality of microphones, 
 retrieving a second statistical measure of individual object-free impulse responses from the plurality of microphones, and 
 comparing the first statistical measure with the second statistical measure to determine if an object is near the device. 
 
     
     
       12. The control circuit of  claim 11  wherein the first statistical measure is a first variance and the second statistical measure is a second variance, wherein the first variance is calculated using differences between the individual impulse responses and a mean impulse response that is a linear combination of the individual impulse responses for the plurality of microphones. 
     
     
       13. The control circuit of  claim 12  wherein the linear combination of the individual impulse responses for the plurality of microphones are weighted with linear weights chosen such that the variance is minimized. 
     
     
       14. The control circuit of  claim 11  wherein the output signal includes at least one of music or speech and wherein it is determined that an object is near the device if the difference between the first statistical measure and the second statistical measure is larger than a predetermined threshold. 
     
     
       15. The control circuit of  claim 11  further providing one or more echo cancellers configured to mitigate effects of at least one of common signals and other acoustic sources in the vicinity of the electronic device. 
     
     
       16. The control circuit of  claim 11  wherein output signals are provided to a plurality of loudspeakers in the device such that the plurality of loudspeakers radiate more acoustic signal in a first direction than in a second direction. 
     
     
       17. The control circuit of  claim 16  wherein a plurality of equalization filters are coupled to the plurality of loudspeakers, at least one of the plurality of equalization filters being different from the remaining plurality of equalization filters. 
     
     
       18. The control circuit of  claim 11  further providing a plurality of echo cancellers configured to estimate the individual impulse responses from the plurality of microphones. 
     
     
       19. The control circuit of  claim 11  wherein the control circuit is configured to perform the analysis operations based at least in part on a selected time-domain region. 
     
     
       20. A method for determining if any object is near an electronic device that includes a loudspeaker and a plurality of microphones within a device housing, the method comprising:
 providing an output signal to the loudspeaker that includes at least one of speech or music;
 receiving input signals from the plurality of microphones, wherein the input signals are generated by the plurality of microphones sensing sounds output by the loudspeaker based on the output signal, and
 performing analysis operations including:
 determining, based on the input signals, a first statistical measure of individual impulse responses from the plurality of microphones, 
 retrieving a second statistical measure of individual object-free impulse responses from the plurality of microphones, and 
 comparing the first statistical measure with the second statistical measure to determine if an object is near the device. 
 
 
 
 
     
     
       21. The method of  claim 20  wherein the first statistical measure and the second statistical measure are calculated using differences between the individual impulse responses and a mean impulse response that is a linear combination of the individual impulse responses for the plurality of microphones. 
     
     
       22. The method of  claim 21  wherein the linear combination of the individual impulse responses for the plurality of microphones are weighted with linear weights chosen such that variance is minimized. 
     
     
       23. The method of  claim 20  wherein it is determined that an object is near the device if the difference between the first statistical measure and the second statistical measure is larger than a predetermined threshold. 
     
     
       24. The method of  claim 20  further comprising providing output signals to a plurality of loudspeakers in the device such that the plurality of loudspeakers radiate more acoustic signal in a first direction than in a second direction. 
     
     
       25. The method of  claim 20  comprising performing the analysis operations based at least in part on a selected time-domain region.